There are TWO K-mount 135mm/2.5 lenses. One has the better coating, and they are of different optical formulas. The less expensive one is a 4 element design with a 52mm filter thread, the "better" one is a 6 element design with a 58mm thread. You can go to Boz's site and read about both lenses.
I've had both, the SMC Pentax with the 58mm thread is clearly superior in every way (imo), but the Takumar version can be a good value and is certainly a useful optic. Shel > [Original Message] > From: Glen > For what it's worth, the lens I was asking about is the K-mount version. > I'm not sure what difference that might make, other than the SMC coating. > > take care, > Glen
